Untersuchung zur Expression und Funktion von HCN-Kanälen in Photorezeptoren und Bipolarzellen der Mäuseretina

Thiel, Frank

Dissertation / PhD Thesis

Untersuchung zur Expression und Funktion von HCN-Kanälen in Photorezeptoren und Bipolarzellen der Mäuseretina

Thiel, F. (Corresponding author)FZJ*

2006
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Berichte des Forschungszenrums Jülich 4202, VI, 99 p. (2006) = Köln, Univ., Diss., 2005

Please use a persistent id in citations: http://hdl.handle.net/2128/473

Report No.: Juel-4202

Abstract: The aim of this study was to examine the expression and the functional properties of HCN- channels (hyperpolarization-activated and cyclic nucleotide-gated) in photoreceptors and bipolar cells of the mouse retina. The expression pattern of the four HCN channel isoforms HCN1 - 4 was studied in retinal sections using immunocytochemistry with isoform-specific antibodies. The stainings were analysed using confocal laser scanning microscopy. In the mouse retina HCN1 is the predominantly expressed isoform. HCN1 could be detected in rods and cones as well as in type5 and type7 bipolar cells. HCN2, HCN3 and HCN4 are not abundantly expressed in the mouse retina. HCN4 was expressed in type 3 bipolar cells. HCN2 and HCN3 could not be found in photoreceptors and bipolar cells. These isoforms were mainly expressed in amacrine and ganglion cells. In retinal slices photoreceptors and bipolar cells were recorded electrophysiologically in the whole-cell mode of the patch-clamp technique to study the activation kinetics and the midpoint potential of activation of HCN channels. During the recording the cells were filled with dyes and were subsequently morphologically identified. The properties of the retinal HCN1 channels differ to some extend from those of heterologically expressed HCN1 channels. The properties of the HCN1 channels also vary between different cell types. This could mean, that HCN1 channels are modulated in the retina. To record retinal light-responses, a genetically modified mouse strain was used in which the gene coding for HCN1 has been deleted - “HCN1 knockout”. Electroretinogramms (ERG) were recorded in vitro from wildtype retinae and HCN1 knockout retinae. In HCN1 knockout retinae the B-wave of the ERG was slightly elongated. This could reflect extended lightresponses of the photoreceptors. In the scotopic flicker-ERG the frequency transfer is slightly reduced in knockout retinae. Application of the HCN channel blocker ZD7288 also slightly reduced the frequency transfer in wildtype retinae. The study provides first insights into the role of HCN1 channels in the generation of lightresponses.

Note: Record converted from VDB: 12.11.2012; Institut für Biologische Informationsverarbeitung
Note: Köln, Univ., Diss., 2005

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